-LRB- CNN -RRB- -- The dreadful shooting sprees of the past few months , which claimed dozens of innocent lives , shocked and unnerved millions of Americans . The specter of some heavily armed madman turning a theater , a temple , a mall or a school into his personal battle zone has become all too real and terrifying .

The latest episode still unfolding in Southern California implicates , oddly enough , a former Los Angeles police officer , 33-year-old Christopher Jordan Dorner , who allegedly is seeking redress for perceived mistreatment by the LAPD . Dorner was a member of the department for three years before losing his badge in 2008 , reportedly for lying about a fellow officer . When he was unable to win back his job , murder became , as a manifesto attributed to Dorner put it , `` a necessary evil '' for him to prevail in the face of racism and injustice .

LA cops talked by suspect , and brutal past

Other than the alleged gunman 's former profession , this case is actually quite prototypical of the nearly two dozen massacres that occur each year in the United States . It is a story that my Northeastern University colleague Jack Levin and I have seen time and time again in our several decades of research on this extreme form of violence . By looking closely enough , one can usually make some sense of seemingly senseless behavior .

The notion of a deranged gunman who suddenly snaps and goes berserk is more myth than reality . Rather , mass murderers act methodically and with purpose . And unlike the shooting sprees in Aurora , Newtown and elsewhere , in which victims who were unknown to their assailants had the horrible misfortune to be in the worst place at the worst time , most mass murders involve people specifically targeted for specific reasons .

Mass murderers tend to be middle-aged men who see themselves as victims of injustice . Although bitter , resentful and full of despair , they see others , often the former boss or supervisor , as the people who are to blame for their miserable existence . Indeed , the workplace is one of the more familiar venues for mass murder , going way back to the 1980s when `` going postal '' became part of our everyday vernacular .

Manhunt reminiscent of D.C. sniper case

Typically , we see a former employee in public service or private industry who feels mistreated and wronged . Believing that his firing is patently unjust , and with nothing left to lose , he decides sooner or later to become the powerful one who will do the `` firing . '' When he is deprived of his financial security , sense of purpose and dignity , the idea of getting even becomes all consuming .

As I write this on Day Six of the L.A. area manhunt , the terror enveloping the region is combined with anxious uncertainty over when the threat will finally be over and , more critically , whether the victim count will rise before the alleged assailant is found dead or alive . Already five people have been shot -- the daughter of the union representative who participated in Dorner 's unsuccessful grievance hearing and her fiance were fatally wounded , as was one of three police officers gunned down in the continuing rampage .

These five victims are actually surrogates , in what is known as `` murder by proxy . '' Even when the primary targets are not readily available , others may be viewed as guiltyâ $ '' and may be assaulted -- simply because of their association . Meanwhile , dozens more among the alleged gunman 's hit list of enemies remain on edge and in hiding until it is safe to resurface .

Not surprisingly , one of the more prominent features to the usual mass-murder profile is access to a powerful enough weapon to achieve an expansive deadly plan . Particularly frightening in the ongoing L.A. drama , of course , is the marksmanship skills that Dorner undoubtedly acquired through his careers with the Navy and in law enforcement , giving added significance to the phrase , `` armed and dangerous . ''

Alleged cop-killer 's manifesto details threats

Adding insult to injury , the man at the center of attention is likely thrilled . If he is like most mass murderers , it is not the spotlight that he is enjoying , but the satisfaction of payback . Others have been made to suffer , as he has in the past . The big question is how many more will be harmed in his methodical and deliberate quest for revenge .

The opinions expressed in this commentary are solely those of James Alan Fox

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James Fox : LA rampage case is typical of mass murders ; like most , planned , methodical

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He says mass murderers tend to be aggrieved middle-aged men , aiming to regain ` power '

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He says in Dorner case , some killed were not actual targets , but cases of ` murder by proxy '

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Fox : Assailant usually thrilled at attention , satisfaction of ` payback '